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Engine stall while driving

C

Coldwaves

New member
The car is a 2005 Pontiac Grand Prix with 3800 series 3 engine natural aspiration.

I was driving on highway at about 65mph and the engine stalled (no response to gas pedal and engine rev fell. I don't think the rev on tachometer fell to 0 but I do not remember exactly.). I lost power steering of course but I managed to stop it on the side of the road. After that, I can restart the car but it is idling rough (it feels like not all the six cylinders are running. It is similar to how the engine sounds and feels when I had a misfire due to faulty ECM a few years ago). I tried to restart it a few times and it always restart and behave the same as I described. No check engine light. All light on dashboard functions because they are light up when I put key into "I". The tail pipe smells like it is running rich (again like how it smells when I had two cylinder misfired a few years ago). The car restart and the driving drive the car onto the towing truck. It is now sitting in the shop. I have to wait until Monday to get it fixed.

I am puzzled since there is no check engine light. If it is a misfire due to a faulty spark plug or coil or ECM, I assume that check engine light will be on. Plus the spark plug and wires are replaced 20000 miles ago. Air filter was replaced last year. Could it be a fuel injector or pump? I don't know whether this will trigger check engine light or not. And the car should sputter before it died. But it did not. It drives totally fine.

My suspicion is crank or cam shaft position sensor. Another relevant symptom is that the car start up very smoothly when cold but seems to struggle to start when it is warm (it will start thought just not start as smooth as it is cold).

Any insights will be appreciated.
 
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Scottydoggs said:
crank sensor never sets the code for it. if its just random stalling, id start with a crank sensor.
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Thanks! I appreciate your insights. While you replied, I edited my post and that's my suspicion although I don't know enough about crank sensor. Would struggle to start when warm be a symptom for a bad crank sensor?

And it always restart fine after the engine stall and runs/idles rough. Can a car idling rough with a bad crank sensor?
 
Scottydoggs said:
what year and engine you got there? could be a bad fpr. and maybe the crank sensor together.
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Sorry I did not include the model and year. I will edit the original post.

It is a 2005 Pontiac Grand Prix base model. Engine is the 3800 series 3 natural aspiration.
 
not the fpr then. back to a crank sensor.

cat could be clogged up too, them na engines love to clog the cat. but that would come with the car feeling like its lost a lot of power. and the cel would flash when you floor it.
 


Scottydoggs said:
not the fpr then. back to a crank sensor.

cat could be clogged up too, them na engines love to clog the cat. but that would come with the car feeling like its lost a lot of power. and the cel would flash when you floor it.
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Thanks! It seems the crank sensor could be the cause.

I haven't floored it but I did not feel any lose of power. No check engine light either. It drives totally fine and then just suddenly stalled. The cat was replaced with a OEM one four years ago and I only drove less than 25000 miles on it. I hope GM's cat is not that bad......
 
check the crank sensor harness for damage while doing the gob, they tend to get old and brittle and get cracks in the insulation, then it fails.
 
Scottydoggs said:
check the crank sensor harness for damage while doing the gob, they tend to get old and brittle and get cracks in the insulation, then it fails.
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Thanks a lot for the insights. I will check that for sure. I also used the AC for the first time in a while but I don't know whether this is related to the engine stall problem.
 
I took the car to the shop and they told me that it is a faulty ignition coil. It is puzzling to me that a ignition problem did not set the check engine light. I guess I have never let the car run for a long time after it died so the engine light does not have enough time to show up. But I will try to talk to the mechanic to see how he did the diagnostic. I will report back what I found in more details.
 
I had an ICM fail on my 00 GT this exact way. Just slowly came to a stop with no amount of engine response from the pedal. Then when it would start it ran like crap. I also found a cracked coil at the same time. Swapped ICM and coil and it fired right up like nothing happened.
 


FordMan77 said:
I had an ICM fail on my 00 GT this exact way. Just slowly came to a stop with no amount of engine response from the pedal. Then when it would start it ran like crap. I also found a cracked coil at the same time. Swapped ICM and coil and it fired right up like nothing happened.
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Exactly. Eventually I have to replace the ignition control module and one ignition coil. The car runs fine after that. The only left problem is that the misfire destroyed the catalytic converter so I have a P0420 code now. This is the second time in four years that the ICM failed and then the catalytic converter failed consequently. I love my 05 Grand Prix but I am more inclined to replace it with something newer and more reliable.
 
My 97 GTP is acting something like this. It seems to be heat related. It will start just fine, idle normal, and drive normal for anywhere from 2 to 15 minutes, then start chugging and eventually stall. With Torque OBD connected once it starts to stall the vacuum reading stays at 0.04, no boost or vacuum. I found the vacuum tee under the snout disconnected, but replacing it did not solve the problem. It has thrown me a code, P0121: Throttle/Pedal Position Sensor/Switch A Circuit Range/Performance Problem, so I replaced the TPS with another I had off another TB. Same issue. Harness seems OK, not rubbing on anything. Once it stalls, it wont start for anything, but if you wait approx 15 minutes starts right up like nothing is wrong. Could it be something as simple as ICM?
 
Could very well be. Might be getting heat soaked and then failing. Any ICM from a 3800 car should work if you have someone around that has one that you could "borrow" long enough to troubleshoot. If it is the ICM, then off to the junkyard you go.
 
I tend to agree with the crank sensor theory, only because I had a Jeep that did the same thing, stalling while driving then after it cooled down it started and ran again. I brought it into the shop multiple times but by the time it got to the shop the problem was gone, and they couldn't figure anything out. After exhaustive research online, I took it in and told them to replace the crank sensor. They called back an hour later and said they didn't think it was the crank sensor. I said, maybe you misunderstood, I told you to replace the damn sensor. They did and it ran happily ever after, at least until I sold it a few years later.
 
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